10x wasn’t meant to be taken literally, but my point is that the complexity of online game development is exponentially higher than local-only.
Even the most simple mechanics, moving an object, shooting another player, using physics vehicles or objects - these often require a lot of additional supporting systems (Prediction/Rewind, Lag Comp, Anti-Cheat to name a few) that aren’t trivial to build and even less trivial to test properly. There are countless additional considerations for online games that aren’t relevant to local games. It shouldn’t be taken lightly.